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Kelvin shunt with AD5253

Question asked by dvosp on Dec 12, 2011
Latest reply on Dec 19, 2011 by prb

Hi,

 

I'm amplifying the output of a 100mohm 4 terminal (kelvin) shunt with the AD8253.  I'm using a lab quality calibrator as the signal (current) source.  Problem I'm having is when injecting a DC current through the shunt; I have a lot of 50Hz coupling into the output of the AD8253.  Measuring with a scope accross the inputs shows no 50Hz content.  I have tried a variety of bias resistors from inputs to AGND (as low as 10k).  Injecting a 50Hz current results in a output signal that beats with mains.

 

How can I minimize this effect with the AD8253?

 

Regards

Pierre

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